To begin with, the Sunday paper.
My grandma, my dad, my neighbor and sometimes a friend of mine kindly save them for me. So I usually have 3 sets of the Sunday coupons. If they didn't do that for me I would definitely buy at least 2 papers per week because the savings way more than covers the cost of the papers.
Below are all my organized coupons. They're in my old baseball card holders. I wish I could say that I invented this system but...
The second place I get my coupons is online. There are tons of internet coupons now. The downside is that you have to download a coupon printer. I've been doing it for over a year and I haven't had any problem with it. But I know some people don't like to download things.
Here's my favorite source for online coupons: coupons.com
You can usually print at least 2 of each. These reset quite frequently. I usually print out the ones I think I'll use and then wait for a sale to decide if I want to print and others. I also put my printer on the setting that uses less ink. Also I only have black ink in the printer right now since color is so much more expensive.
Another good source is: smartsource
The brands themselves often have coupons if you go to their website.